Forensic Science – Toxicology

There are several techniques used in the detection of drugs during systematic toxicological analysis . These techniques are useful methods for the detection and identification of drugs that are valuable in a variety of contexts such as the criminal justice system , and pre-employment screening . The suitability and availability of each technique varies depending on the drug being studied . Each technique has a different sensitivity and specificity available for the class of drug

Gas Chromatography and Thin-Layer Chromatography

Gas Chromatography (GC ) is an instrument used to separate volatile [banner_entry_middle]

components of a liquid sample . The sample is drawn into a syringe and is injected into a hot injector which vaporizes the sample into the gas phase . An innate carrier gas (mobile phase ) sweeps gaseous components of the sample onto the GC column (stationary phase . The components of the sample partition between the two phases and are individually recorded as they reach the detector at end of the column at different times . Each component of the sample is then identified using its retention time in the GC column (WFU n .d

Thin-Layer Chromatography (TLC ) is a simple and inexpensive procedure that is often used to provide information on number of components in a compound or to indicate the extent of progress of a chemical reaction (WPI n .d . In this technique , a small quantity of a sample is blotted on a TLC plate which moves up via capillary action of a solvent . The substances are then identified using by their their so-called Rf values The Rf value for a substance is the ratio of the distance that the substance travels compared to the distance that the solvent travels up the plate (WPI n .d

Methadone

Methadone is a synthetic narcotic analgesic which is used in many countries as substitution therapy for heroin addiction (Horakova and Valentova , 2004 ,

.1 . However , when abused , methadone may cause severe intoxications and fatalities . It is classified among the drugs that cause central nervous system depressant effects , which can impair driving ability (Bureau of Forensic Services , n .d . Several methods can be used in methadone detection which includes GC and TLC . In a study on the determination of methadone in urine (Horakova and Valentova 2004 ,

.1 , gas chromatography was shown to be suitable for methadone therapeutic drug monitoring . However , whereas the chromatographic separation was completed within 13 min , the whole procedure from the extraction to determination of methadone and EDDP in urine took 4 – 5 hours to complete

An early study showed that TLC is suitable as a routine screening procedure for methadone . McIntyre et al (1975 ,

.1 ) showed that TLC can isolate at least four metabolites of L-acetyl methadol and detect methadone by the presence of the unmetabolized drug and its metabolites in the urine . Using the technique , the investigators showed the TLC can be used as a simple means of distinguishing methadone-containing specimens from those that contain L-acetyl methadol Codeine

Codeine is used as a narcotic analgesic drug prescribed for pain relief… [banner_entry_footer]